Verses with the word liar in the Old Testament (5 verses):

Job 24:25
And if it be not so now, who will make me a liar, and make my speech nothing worth?

Proverbs 17:4
A wicked doer giveth heed to false lips; and a liar giveth ear to a naughty tongue.

Proverbs 19:22
The desire of a man is his kindness: and a poor man is better than a liar.

Proverbs 30:6
Add thou not unto his words, lest he reprove thee, and thou be found a liar.

Jeremiah 15:18
Why is my pain perpetual, and my wound incurable, which refuseth to be healed? wilt thou be altogether unto me as a liar, and as waters that fail?